(1) Field of the Invention
The present invention relates to a toner cartridge for use in an image forming apparatus such as a copier, printer, facsimile machine or the like.
(2) Description of the Prior Art
In a typical image forming apparatus, an image is reproduced and recorded on a sheet of printing paper by the electrophotographic process comprising the steps of: forming a latent electrostatic image on the photoconductor, supplying toner from the developing device to the photoconductor so as to develop the static latent image into a toner image and transferring the toner image onto the printing paper. The toner left on the photoconductor is removed as waste toner by the cleaning unit.
Since the waste toner thus removed is different in charge characteristics from unused toner and is degraded with paper particles resulting from printing sheets and other foreign substances, it is generally collected by a waste toner container which is provided separately from the unused toner container. Here, the amount of discharge of waste toner may differ depending on the usage environment of the machine, the quality of printing paper and the like. Further, the amount of waste toner may increase due to some unexpected events in the transfer step. Therefore, the waste toner container is so designed as to afford a sufficient margin as to its volume. As a result,the entire apparatus will become large. There is still a risk that the waste toner container might become full of waste toner and could not keep any more. In this case, the waste toner will leak out inside the machine and will contaminate the machine interior.
To deal with this, Japanese Patent Application Laid-Open Hei 4 No. 237079 discloses a configuration as shown in FIGS. 1 and 2, in which an unused toner container 102 and waste toner container 101 are provided so as to adjoin to each other with a partitioning wall 111 in-between, and the partitioning wall 111 is formed with an opening 103 having a shutter 110 which can be opened by the pressure of the toner in waste toner container 101 so as to allow the toner to move from the waste toner container 101 side to the unused toner container 102 side. In accordance with this configuration, when the waste toner container 101 becomes full of toner and hence is increased in pressure, the shutter will automatically open so that the waste toner can move into unused toner container 102. Therefore, it is possible to make the waste toner container 101 compact while preventing waste toner leakage. The waste toner having moved to unused toner container 102 through opening 103 is mixed with unused toner by a toner conveying and agitating element 109 in unused toner container 102. In the drawings, 104 designates a photoconductor, 105 a cleaning unit, 106 a waste toner conveying means, 107 a waste toner collecting pipe and 108 a developer roller.
Japanese Patent Application Laid-open Hei 8 No.44179 and Hei 5 No.341697 disclose waste toner container configurations for efficiently storing waste toner collected therein by uniformly distributing it. For example, as shown in FIG. 3, a toner conveying element 118 is provided in a waste toner container 116. With this arrangement, the waste toner having passed through a waste toner conveyance passage 119 is delivered into waste toner container 116 through waste toner collecting port 119a, and is efficiently collected in waste toner container 116 by means of toner conveying element 118. Resultantly, this configuration makes it possible to make waste toner container 116 compact. In the drawing, 115 designates an unused toner container, 115a an unused toner supplying port and 117 a partitioning wall.
For the former toner cartridge, waste toner moved to the unused toner container is mixed with unused toner by means of the toner conveying and agitating element inside the unused toner container, but there occur cases where waste toner is directly supplied to the toner supply means due to an insufficiency of the agitation. As a result, the toner image cannot be formed correctly at the developing step and image degradation will occur at the transfer step.
For the latter toner cartridge, the waste toner container is able to efficiently store the waste toner by its being evenly distributed, but since no waste toner will move from the waste toner container to the unused toner container, there is a limit to the downsizing of the waste toner container. Further, this configuration needs a weight detecting means or the like for detecting the state of the waste toner container being full. Resultantly, the apparatus configuration will become complicated and increased in cost.
The present invention has been devised in view of the above circumstances, it is therefore an object of the present invention to provide a toner cartridge for an image forming apparatus which eliminates the necessity of providing a separate waste toner container by collecting waste toner into an unused toner container without causing any image degradation, to thereby make the apparatus compact and reduce the cost.
In order to achieve the above object, the toner cartridge for an image forming apparatus of the present invention is configured as follows:
In accordance with the first aspect of the present invention, a toner cartridge for an image forming apparatus, includes: a toner container for holding toner; a toner supply element disposed inside the toner container for supplying the toner to a developing device of the image forming apparatus; and a toner conveying and agitating element for conveying the toner to the toner supply element whilst agitating the toner inside the toner container, and is characterized in that the toner container has a partitioning wall disposed therein for partitioning the toner container interior whilst allowing communication between the partitioned compartments, a waste toner collecting port for receiving the waste toner collected by a cleaning unit of the image forming apparatus is formed in one of the partitioned compartments, and a toner agitating element for mixing waste toner and unused toner is arranged inside the partitioned compartment having the waste toner collecting port.
In accordance with the second aspect of the present invention, the toner cartridge for an image forming apparatus having the above first feature is characterized in that a flexible element is attached to the toner agitating element.
In accordance with the third aspect of the present invention, the toner cartridge for an image forming apparatus having the above first feature is characterized in that the waste toner collecting port is formed at such a position that waste toner will enter the toner container in almost the same direction as that in which the toner agitating element rotates.
In accordance with the fourth aspect of the present invention, the toner cartridge for an image forming apparatus having the above first feature is characterized in that the partitioning wall is arranged at a position exterior to the end of the toner supply element.
In accordance with the fifth aspect of the present invention, the toner cartridge for an image forming apparatus having the above first feature is characterized in that the toner agitating element and toner conveying and agitating element in the different compartments partitioned by the partitioning wall are driven by a common rotary shaft.
In accordance with the sixth aspect of the present invention, the toner cartridge for an image forming apparatus having the above first feature is characterized in that the toner agitating element and toner conveying and agitating element in the different compartments partitioned by the partitioning wall are driven at different rotational rates.
In accordance with the seventh aspect of the present invention, the toner cartridge for an image forming apparatus having the above sixth feature is characterized in that the toner agitating element and toner conveying and agitating element in the different compartments partitioned by the partitioning wall are driven by a common drive source.
According to the present invention, the waste toner collected by the cleaning unit of the image forming apparatus is charged into the toner container through its waste toner collecting port so that the collected waste toner is mixed with unused toner by the toner agitating element. The thus mixed toner is transferred from the first compartment to second compartment partitioned by the partitioning wall. Then the toner is further mixed by the toner conveying and agitating element and supplied to the toner supply element.
According to the present invention, since the flexible element is adapted to rotate with its distal end following the inner surface of the toner container when waste toner and unused toner are mixed by the toner agitating element, a further enhanced mixing can be effected.
According to the present invention, the waste toner received through the waste toner collecting port is agitated without fail before it is transferred to the second compartment of the toner container.
According to the present invention, the toner mixed on the first compartment before passing through the partitioning wall can be transferred to the second compartment and agitated once again therein and supplied to the toner supply element by the toner conveying and agitating element.
According to the present invention, the toner agitating element and toner conveying and agitating element are driven by a common drive source.
According to the present invention, the amount of toner agitated by the toner agitating element and transferred from the first compartment to the second compartment is differentiated from the amount of toner supplied to the toner supply element by the toner conveying and agitating element.
According to the present invention, the toner agitating element and toner conveying and agitating element having different rotational rates are driven by a common drive source.